The trading deadline is approaching in Major League Baseball, and as it does every July, that means good players are changing teams—and changing roles—this summer. Opportunity is everywhere for the fantasy baseball owner that jumps on roster changes, too, since grabbing the right player after a trade can make a huge difference in the league standings come September.

This is not news, as the MLB trade frenzy that occurs between the All-Star Game and July 31 every season is a well-documented ritual. However, it’s always surprising that so many fantasy baseball owners fall asleep at the wheel during this most volatile time in the MLB regular season. Don’t let that happen to you.

The frenzy is a double-sided wonder: Contending teams acquire new players to augment their roster strength, and non-contending teams give new opportunity to undervalued players that probably weren’t drafted in any fantasy league last spring. Thus, every team in the the sport has new faces filling new roles, and that means a chance for boosting all of your fantasy team’s numbers.

Paying close attention to the daily—sometimes even hourly—news updates from MLB can make a huge impact on the standings in your league. Don’t be the last owner to find out that your starting third baseman just became bench depth, and his replacement now belongs to your biggest fantasy-league rival. That’s pretty much the nightmare scenario.

Players to Get On Your Roster Now

1. Tyler Clippard, RP, Arizona Diamondbacks: With Brad Ziegler going to Boston, Clippard should get the new closer role for the D’backs. He saved 32 games for Washington in 2012, and he saved 17 games for Oakland in the first half of 2015. He’s the best option in the desert right now for saves, and while Arizona may not be leading a lot of games late, Clippard’s experience make him the man to turn to in the Diamondbacks’ bullpen.

2. Kennys Vargas, DH, Minnesota Twins: Back in 2014, he showed some promise as an MLB hitter, and now Vargas is back with the Twins after playing a lot in the minor leagues due to contact issues. However, his power is real, and as long as he gets some plate appearances in Minnesota, he should produce. In 120 MLB games in his career, Vargas has hit 17 home runs and posted 59 RBI. His walk rate is up right now, so perhaps that’s a good sign for the future.

3. Koji Uehara, RP, Boston Red Sox: He’s filling in as the closer in Boston right now as Craig Kimbrel recovers from a knee injury. Uehara notched 72 saves from 2013-2015 for the Red Sox, so the team will be comfortable with him in the closer’s role, even after Kimbrel comes back. That really carries value right up to the final weekend of the season in early October. Don’t think twice about this one.

4. Brandon McCarthy, SP, Los Angeles Dodgers: Even at age 32, he carries fantasy value—for a few reasons. First, he’s pitching for the Dodgers, and that means some wins will come his way even if he doesn’t pitch well. Second, McCarthy pitched well for postseason-contending teams in Oakland (2012) and New York (2014) recently, so he’s not going to be fazed by the pressure of pitching in Los Angeles. His early numbers right now are impressive; just don’t expect them to last. Simply expect some wins and solid ERA/WHIP contributions.

Players to Sit/Drop This Week

1. Billy Burns, OF, Oakland Athletics: Do not waive him, because his speed is real. Burns just needs some time in the minors to adjust his approach at the plate, and he will be back in Oakland and ready to run again. He’s been a disappointment this year at the plate after a good rookie season in 2015, but again, his speed has value—and Burns will be back soon. If you’re not convinced of this, then trade him to someone that is convinced. The 10-15 stolen bases he will get later in the season can make a difference in any league.

2. Brad Ziegler, RP, Boston Red Sox: As noted above, his new destination isn’t favorable for save opportunities. The Red Sox will use Ziegler as a set-up man, and he’s going to be low in the pecking order in Boston when it comes to picking up saves now. These are the kinds of situations that stink for fantasy owners, of course, but that’s the game we all agree to play when we sign up. Hopefully, Ziegler’s 18 saves this season helped you out already, but he’s now relatively worthless in fantasy baseball.

3. Matt Harvey, SP, New York Mets: This is more of a blow to real-life baseball than to fantasy baseball, as Harvey’s health has been sporadic during his MLB career. He missed all of 2014, for example, and this year, Harvey leads the National League in losses while putting up the worst ERA of his career, by far. Obviously, something was wrong. Either way, he’s done for the season, so let him go and approach with caution in 2017 drafts.

4. C.J. Cron, 1B, Los Angeles Angels: If you were fortunate enough to grab Cron this spring, consider yourself lucky to have gotten 11 HRs and 50 RBI out of him in only 77 games. However, his hand injury all but makes him valueless for the second half of the season. He will be out almost two months now, and hand injuries aren’t good ones for hitters to return from quickly even once they heal. Target him next spring in drafts, though.

Sam McPherson is a freelance writer covering baseball, football, basketball, golf and fantasy sports for CBS Local. He also is an Ironman triathlete and certified triathlon coach. Follow him on Twitter @sxmcp, because he’s quite prolific despite also being a college English professor and a certified copy editor.